Router not releasing DHCP addresses, can I clear?
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12-29-2007 08:01 AM - edited 03-03-2019 08:04 PM
I am using a Cisco 877, but I have noticed I get a new IP everytime, but the next one up, there are only 2 PC's on this router. I get an IP of 192.168.2.11, then tomorrow it will be 192.168.2.12, then 13, 14 etc, surely it should release the IP after a day or 2 and reuse the IP's at the beggining of the scope?
ip dhcp pool client
import all
network 192.168.2.0 255.255.255.0
default-router 192.168.2.100
dns-server 87.86.18.1 90.20.23.9 190.72.0.9
lease 0 2
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12-29-2007 08:10 AM
Are you by any chance having filters on the interface?
I've seen this behavior before when applying an access-list to the interface of the DHCP clients.
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12-29-2007 08:33 AM
Yeah I do, here is the config. It's a 837 not a 877, sorry about that.
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12-29-2007 09:43 AM
Just cleared the arp, but my pc wants to continue to now have 192.168.2.20, why not 192.168.2.11 or 12 (the start of the DHCP scope)?

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12-29-2007 09:47 AM
Actually I believe the IOS DHCP server will use linearly the pool unless the client requests an available address.
Do "show ip dhcp pool" to see which address will be handed out at the next request .
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12-29-2007 10:05 AM
Here it is:
H0m3#sh ip dhcp pool
Pool client :
Utilization mark (high/low) : 100 / 0
Subnet size (first/next) : 0 / 0
Total addresses : 254
Leased addresses : 1
Pending event : none
1 subnet is currently in the pool :
Current index IP address range Leased addresses
192.168.2.21 192.168.2.1 - 192.168.2.254 1
H0m3#
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12-30-2007 02:01 AM
Hmm, just rebooted the router and it fixed it.

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12-30-2007 05:43 AM
Well,you should now be able to observe, as mentioned before, that the router allocated addresses in a linear fashion, spanning the full scope, unless the client request otherwise.
